This Background section of this specification is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued, and thus should not be considered prior art unless it is expressly so stated.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP: third generation partnership project;    ACK/NACK: acknowledgement/negative acknowledgements;    AP: access point;    API: application programming interfaces;    ACCS: autonomous component carrier selection;    BAC: blind admission control;    CDF: cumulative distribution function;    CUE: cellular user equipment;    CQI: channel quality indicator;    CRC: cyclic redundancy check;    CSI: channel state information;    DAC: distributed admission control;    D2D: device to device;    D2DBSIE: device to base stations information element;    D2DIE: device to device information element;    D2DIE2: device to device information element 2;    dB: decibels;    dBm: decibel-milliwatts;    eNB or eNodeB: E-UTRAN Node B (evolved Node B/base station); used interchangeably with “access point”;    EPC: enhanced power control;    E-UTRAN: evolved UTRAN (LTE);    FDM: frequency division multiplexing;    HII: high interference indication;    IP: Internet Protocol;    LTE: long term evolution;    LTE-A: LTE advanced;    MAC: media access control;    M2M: machine-to-machine;    OAC: optimal admission control;    OLPC: open loop power control;    PD: power control function;    PDCCH: physical downlink control channel;    PHY: physical layer;    PMI: pre-coding matrix index;    PRB: physical resource block;    ProSe: proximity-based services;    PSCCH: physical sidelink control channel;    PSSCH: physical sidelink shared channel;    PSD: power spectral density (dBm/Hz);    RSRP: reference signal receive power;    RE: resource elements;    RI: rank indicator;    RS: reference signals;    SCI: sidelink control information;    SINR: signal to interference plus noise ratio;    TPC: transmit power control;    UE: user equipment, where UEs is the plural;    UL: uplink (UE to eNB);    UPP: universal plug and play;    UTRAN: universal terrestrial radio access network; and    WLAN: wireless local area network.
The following definitions of terms used herein are applicable:    3GPP: The 3rd Generation Partnership Project provides specifications that define 3GPP technologies;    “access point”: In cellular networks like LTE-A, it is a conceptual point within the radio access network performing radio transmission and reception: An access point is associated with one specific cell, i.e. there exists one access point for each cell. It is an end point of a radio link. In other wireless systems like Wi-Fi, it is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards; “Access point” in this application refers to a conceptual point within the radio access network, unless otherwise specified;    “base station” or “eNodeB” or “eNB”: A base station is a network element in radio access network responsible for radio transmission and reception in one or more cells to or from the user equipment. Each eNodeB has a baseband processing unit. Each baseband processing unit is connectable to multiple radio units (either remote radio heads or radio cards), which enable transmit and receive functions involving radio frequency signals. Thus, each radio unit is connected to one or more antennas serving a particular direction, and thus forming a sector or a cell (in the logical naming sense), as shown in FIG. 2B;    “cell”: A radio network area that can be uniquely identified by a mobile terminal from a (cell) identification that is broadcasted over a geographical area from one access point.    “D2DBSIE”: parameters or signalings that carry stastical information of the tolerable performance loss of the primary UEs such as for example, the total amount of interference from the device to device links that is tolerable by the user equipment in an uplink; propagation constants related to a channel model; coverage area for device to device links; and an average sum of channel gain of existing device to device links to the base stations.    “D2DIE”: parameters or signalings that carry statistical information of existing active device to device links, such as for example, density or number of active device to device links; propagation constants related to a channel model; and a coverage area for device to device links.    “D2DIE2”: parameters or signalings sent between adjacent access points or base stations and may include the density or the number of active device to device links in the serving area of the base station and may include a high interference indicator for sidelink communications in the wireless communications network;    “D2DIE3”: parameters or signalings sent from one user equipment of a device to device pair to adjacent base stations to indicate that in the near future, potential transmission between the sidelink (device to device) communications will be scheduled in certain parts of the radio resources, These include bandwidth, frequency division multiplexing (FDM) symbols, or resource blocks, by the device to device pair.    “user equipment” or “UE,” or “mobile terminal” or “terminal” is a device that allows a person to access to network services. The interface between the UE and the network is the radio interface;    “PSCCH”: Physical Sidelink Control Channel, a transmission resource pool and physical channel defined in a sidelink carrying the control information. A physical channel is defined by code, frequency, relative phase (I/Q), or time-slot, and so on; and    “PSSCH”: Physical Sidelink Shared Channel, a transmission resource pool and physical channel defined for a sidelink carrying data.
More and more devices are becoming connected. Market research by others suggests that in 2020 the total number of connected devices will grow from 9 billion today to 24 billion, with half incorporating mobile technologies. These connected devices can be devices such as smart meters, but increasingly all kinds of consumer electronic devices (e.g. photo cameras, navigation devices, e-books, hi-fi equipment, and televisions) are connected. Many of these connections are among devices in close proximity and there is evolving demand for enabling proximity services from different perspectives. This is described in CISCO, “Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update,” 2014. For example social apps, hyper-local marketing and classifieds may be based on proximity.
Proximity will also be a new vector for mobile advertising and there will be growing need to enable new types of advertising for proximity services. For example a customer in a mall will prefer to receive information or ads related to the shops inside this mall, rather than those worldwide.
Many consumer electronic devices will need to communicate with other consumer electronic devices in their neighborhood. For example a photo camera can communicate with a printer, or a media server can communicate with hi-fi equipment.
Providing proximity-based services enables consumers to interact with their proximate environment in a spontaneous and direct way using their smartphone, and thus bring about a huge array of benefits for the consumer, for enterprises and in turn, for the operator.
As a value-added-service, proximity-based services offer the potential for huge gains for operators, including additional revenue gained from the consumers from access to services, from new marketing tools for enterprise customers, and from opportunities for revenue sharing with third-party's via developer Application Programming Interfaces (APIs).
A major economic opportunity of proximity-based services is for mobile operators to hold the rights to the spectrum that enables this functionality. The party holding the rights to the spectrum could act as a gatekeeper, controlling access to the services.
The start-of-the-art research and inventions related to proximity-based services and technologies may be summarized by a discussion of the 3rd Generation Partnership Project (3GPP). The 3rd Generation Partnership Project unites multiple telecommunications standard development organizations and provides the means to define systems for cellular telecommunications and network technologies.
IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6, 5, and 60 GHz frequency bands. The IEEE802.11 is hereby incorporated by reference herein. The IEEE 802.11 specifications are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). In IEEE 802.11, the primary UEs are the devices that communicate directly to the access point while the device to device pair could be two devices that communicate directly to each other. Within 3GPP, Proximity-Based Services (PBS) provide discovery of devices and communications between devices in proximity. Thus, Proximity-Based Services support communication between devices that are physically located close to each other.
Device-to-device (D2D) communications is enabled by cellular networks, e.g. 3GPP infrastructure that provides a generic communication capability that can generate a new revenue source for mobile network operators. As proximity based applications are growing fast, the demand of Device to Device communications will increase dramatically. Developing scalable Device to Device communications for systems like 3GPP is of paramount importance.
The main idea of Device to Device communications is to enable two devices in proximity to communicate directly with each other, re-utilizing the resources of primary cellular networks or using a set of orthogonal resources. Its impact on the performance of existing cellular UEs should be minimal. For example in Long Term Evolution-A, device to device links may share the uplink resources of the cellular network or use orthogonal resources.
When downlink resources are reused, device to device links may cause strong interference towards existing cellular user equipment, whereas in the case of sharing uplink resources, the interference caused by device to device links will affect only the base stations, where the impact has been determined to be less harmful.
As more device to device pairs exist in the network, the interference levels may increase to a point where the performance of both cellular and Device to Device networks could be seriously degraded. Thus, one of the main limitations on the scalability of Device to Device communications is interference control. To solve this potential problem, a careful interference coordination and power control technique is used to have scalable Device to Device communications to assure quality of service to both Device to Device UEs and existing cellular UEs.
When device to device links are added to the system, two main levels of interferences are generated: 1) A first level of interference caused by the cellular network, namely from existing cellular user equipment towards other base stations (inter-cell interference) and from Cellular User Equipment towards device to device links; and, 2) a second level of interference caused by Device to Device network, namely from device to device links towards the base stations and from device to device links towards other device to device links.
The first level of interference includes inter-cell interference. In the uplink of the last generation cellular networks the resources within each cell are allocated orthogonally resulting in zero intra-cell interference. However, the resources are shared by several cells causing inter-cell interference between the Cellular User Equipment and base stations of different cells. This problem is well known and there has been important research done in the last years.
There are numerous studies and proposals that form the background of addressing cellular interference. One proposal includes an adaptive soft frequency reuse scheme that decreases inter-cell interference improving the average throughput per UE. Another recommends an interference aware joint scheduling scheme based on proportional fairness. Others have studied the problem of resource allocation considering the impact of inter-cell interference while maintaining a frequency reuse of one. Studies have been published on the evaluation of the Long Term Evolution Open Loop Fractional Power Control and the closed loop power control considering the impact of inter-cell interference while giving an insight to the proper configuration of the design parameters.
For example, in the conventional power control for sidelink communications, the transmission power control formula for PSSCH or PSCCH is
      P          D      ⁢                          ⁢      2      ⁢                          ⁢      D        =      min    ⁢                  {                                                            P                                  CMAX                  ,                  c                                                                                                                          10                  ⁢                                                                          ⁢                                                            log                      10                                        ⁡                                          (                                              M                                                  D                          ⁢                                                                                                          ⁢                          2                          ⁢                          D                                                                    )                                                                      +                                  P                                      O                    ⁢                                                                                  ⁢                    _                    ⁢                                                                                  ⁢                    D                    ⁢                                                                                  ⁢                    2                    ⁢                    D                                                  +                                                      α                                          D                      ⁢                                                                                          ⁢                      2                      ⁢                      D                                                        ·                  PL                                                                    }            dBm      
where PCMAX,c denotes the maximum UE output power on cell c and MD2D denotes the D2D transmission bandwidth in number of PRBs for the corresponding channel, e.g. PSSCH or PSCCH. PO_D2D and αD2D are the two power control parameters (1215) that are adjustably configured by higher layers for the corresponding channel and transmission mode. Thus, the power control parameters (1215) are configured by higher layers for the corresponding channel and transmission mode. The term PL is the downlink path loss estimate calculated in the UE for serving cell c in dB. This formula protects the serving cell from the interference of the sidelink communications. In special situations where this protection is not needed, the UE can be instructed by the eNB to use the maximum UE output power through D2D grant (i.e., TPC=1).
In Long Term Evolution Inter-Cell Interference Coordination, a proactive indicator, known as the “High Interference Indicator,” can be sent by an Evolved Node B (eNodeB or eNB) to its neighboring Evolved Node B to inform them that it will, in the near future, schedule uplink transmissions by one or more cell-edge user equipment in certain parts of the bandwidth, and therefore that high interference might occur in those frequency regions. As illustrated in FIG. 2A, X2 is the name of the interface that connects one Evolved Node B to another Evolved Node B. S1 is the interface for the communications between Evolved Node B and a Mobility Management Entity (MME).
Neighboring cells may then take this information into consideration in scheduling their own UEs to limit the interference impact. This can be achieved either by deciding not to schedule their own cell-edge user equipment in that part of the bandwidth and only considering the allocation of those resources for cell-center UEs requiring less transmission power, or by not scheduling any UE at all in the relevant Resource Blocks (RBs).
The High Interference Indicator (HII) is comprised of a bitmap with one bit per Resource Block, and, like the Overload Indicator (OI), is not sent more often than every 20 milliseconds. The High Interference Indicator bitmap is addressed to specific neighbor Evolved Node Bs. On the other hand, the Overload Indicator, being a reactive indicator, can be exchanged over an X2 application protocol interface to indicate physical layer measurements of the average uplink interference plus thermal noise for each Resource Block. The Overload Indicator can take three values, expressing low, medium, and high levels of interference plus noise. In order to avoid excessive signaling load, it cannot be updated more often than every 20 milliseconds.